In electrical circuits that use flip-flops as digital mixers, spurious transitions or spikes, generally referred to as glitches, may be generated. In conventional circuits using a flip-flop as a digital mixer, glitches in the output signal are likely to occur when the input signals drift through an in-phase condition. When the input signals change state simultaneously, the mixer flip-flop may or may not be properly clocked and may assume the 0 or 1 states randomly for several successive clocks. As a result, the beat frequency output may include undesirable spurious transitions.
Thus, there is a need for a simple digital mixer that employs flip-flops and prevents the generation of glitches in the beat frequency output even for very low beat frequencies.